Suppressible and universal handgun barrel

ABSTRACT

Provided is a replacement pistol barrel for reliable operation when suppressed and that will universally fit multiple versions of a handgun model.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/946,630, filed Dec. 11, 2019, and incorporates the same herein byreference.

TECHNICAL FIELD

This invention relates to a barrel designed to allow its useinterchangeably on multiple versions of a handgun platform and to allowreliable slide cycling when used with a sound suppressor without extrabarrel length extension.

BACKGROUND

Sig Sauer (“Sig”) has produced a “modular” line of handguns that allow asingle chassis to be used with a variety of grips and a variety ofslide/barrel combinations. This allows the user to change both the size(length of barrel and length of grip) and caliber using just onechassis. The chassis is the “frame,” which is the serialized partconsidered to be the “firearm” under U.S. law. Thus, without purchasingan additional “firearm” the user can reconfigure the handgun in multipleways.

Sig handgun models also come in multiple configurations. For example theSig P320 is available in the “full size” (4.7″ barrel),“compact”/“carry” (3.9″ barrel), and “subcompact” (3.6″ barrel).Additionally, the military version of the Sig P320 (M17/M18) includes aloaded chamber indicator (“LCI”) which requires a rear portion of thebarrel, above the chamber, to include a notch to accommodate the LCI.The Sig P250 is also available in similar multiple configurations. To acertain degree, there is modularity between the P250 and P320, but thereis very limited interchangeability of barrels between configurations,even of the same model, without also changing the slide. So, despitethis “modularity,” a change in caliber requires a change of not only thebarrel (and magazine), but also of the slide. Across a model platform,the barrels and slide for different configurations and/or calibersutilize different dimensional specification for the barrel lock-up block(trunnion), which engages with the ejection port of the slide. Thisengagement keeps the barrel and breach face of the slide locked togetherand delays unlocking until the barrel tilts downward at the breach end,allowing the slide to retract.

“Conversion kits” (also called “Caliber X-Change Kits”) are availablefrom Sig to facilitate modularity. These kits include a barrel, slide,and magazine (and may include another grip). But, because the slide is asignificant cost portion of a “change kit,” it would be desirable tohave a “universal” barrel design that would operate with any of theslides for that model/platform. Specifically, the height of the topsurface of the barrel lock-up block is different for differentconfigurations, so that there is operation-preventing interferencebetween certain barrels and certain slides of different configurations,even within the same model/platform, as the barrel tilts to unlock andallow the slide to retract.

When a pistol is fired, the rearward recoil force (equal and opposite tothe forward force of the projectile) pushes the cartridge case headagainst the breach face of the slide. Because the barrel and slide are“locked” together at this stage of the firing sequence, both the barreland slide initially move to the rear together a limited distance. Indesigns relevant to the present invention, the barrel lugs provide anangled slot that engages with a locking block structure in the framebelow the barrel axis, which forces the rear (chamber) end of the barreldownward as the barrel shifts to the rear. The rearward movement of thebarrel stops when the lugs have fully engaged the locking block. Thatthat point, the rear end of the barrel has moved downward enough toallow the slide to pass over the barrel and continue its rearwardtravel, separate of the barrel, to eject the empty case. The barrel istilted relative to the slide and its in-battery orientation, with theforward end of the barrel slidingly supported by inner surfaces of anopening at the forward end of the slide. As the distance shortensbetween these forward slide surfaces and the pivot point of the lugsengaged with the locking block, the displaced angle of the barrelincreases. This angle is steeper and more pronounced with shorterbarrels, as compared to longer barrels.

Pistols with short barrels can experience operational irregularitieswhen used with a noise suppressor (silencer). Noise suppressors alsoadsorb a significant about of recoil. That recoil force is harnessed tocycle the slide to eject and then chamber a new cartridge. In tiltingbarrel designs (by far the most common), the barrel remains locked withthe slide, keeping the chamber closed, until both the barrel and slidehave moved a predetermined distance to the rear. As described above, thedownward movement (tilt) of the barrel that allows the slide to passover the barrel once the barrel has reached it limit ofrearward/downward travel. The timing of this unlocking relative to theremaining pressure within the barrel is critical to reliable operation.In certain barrel designs, it is the forward top edge of an enlargedtrunnion portion surrounding the chamber that engages/disengages withthe slide to lock the cartridge head against the breach face of theslide until it disengages and allows the slide to pass over thenow-tipped barrel.

Some noise suppressors include a “Nielsen device” or recoil booster thathelps assure sufficient recoil to cycle the slide. The operation ofthese devices is well known. Additionally, the effective length of thebarrel may be increased beyond that necessary for threads (often by asmuch as an additional 0.5″) to extend beyond the slide when the barrelis intended for use with a suppressor. This extra length allows morepropellant powder to burn and can help to increase the recoil to a levelsufficient to cycle the slide when used with a suppressor.

SUMMARY OF THE INVENTION

The present invention provides a “universal” barrel design that willfunction with all slides across the Sig P320 platform and M17/M18platform. A top, forward surface of the barrel portion surrounding thechamber is sloped and a rear notch is provided in the hood extension toreceive a Loaded Chamber Indicator (LCI). If used with a slide that doesnot include an LCI and/or one that accepts a higher lock-up block topsurface, the universal barrel will still function without anydetrimental results. The width od the hood extension is reduced to theminimum dimension within tolerance specifications, allowing it to fit inall slide styles of a model.

By lowering the top forward edge that engages the slide to lock thebarrel, the barrel will unlock at an earlier point in its cycle andwhile the barrel is at a less than fully angled position. The barrel is“fully angled” when its lugs have fully engaged the locking block of theframe and the slide has reached it full rearward recoil position.

Other aspects, features, benefits, and advantages of the presentinvention will become apparent to a person of skill in the art from thedetailed description of various embodiments with reference to theaccompanying drawing figures, all of which comprise part of thedisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Like reference numerals are used to indicate like parts throughout thevarious drawing figures, wherein:

FIG. 1 is an isometric view from above and rear (right side) of a barrelaccording to an embodiment of the present invention;

FIG. 2 is a right side view thereof;

FIG. 3 is a rear end view thereof;

FIG. 4 is a top plan view of a first embodiment barrel in a locked-upposition in a slide having a Loaded Chamber Indicator (LCI);

FIG. 5 is a side elevation view thereof;

FIG. 6 is a top plan view thereof with the barrel in an unlocked,partially tilted position at which the slide can pass;

FIG. 7 is a side sectional view thereof taken substantially along line7-7 of FIG. 6;

FIG. 8 is a similar sectional view enlarged to show detail;

FIG. 9 is a top plan view of the barrel in a locked-up position in aslide not having an LCI; and

FIG. 10 is a side elevation view thereof.

DETAILED DESCRIPTION

With reference to the drawing figures, this section describes particularembodiments and their detailed construction and operation. Throughoutthe specification, reference to “one embodiment,” “an embodiment,” or“some embodiments” means that a particular described feature, structure,or characteristic may be included in at least one embodiment. Thus,appearances of the phrases “in one embodiment,” “in an embodiment,” or“in some embodiments” in various places throughout this specificationare not necessarily all referring to the same embodiment. Furthermore,the described features, structures, and characteristics may be combinedin any suitable manner in one or more embodiments. In view of thedisclosure herein, those skilled in the art will recognize that thevarious embodiments can be practiced without one or more of the specificdetails or with other methods, components, materials, or the like. Insome instances, well-known structures, materials, or operations are notshown or not described in detail to avoid obscuring aspects of theembodiments. “Forward” will indicate the direction of the muzzle and thedirection in which projectiles are fired, while “rearward” will indicatethe opposite direction. “Lateral” or “transverse” indicates aside-to-side direction generally perpendicular to the axis of thebarrel. Although firearms may be used in any orientation, “left” and“right” will generally indicate the sides according to the user'sorientation when shooting; “top” or “up” will be the upward directionwhen the firearm is gripped in the ordinary manner.

Referring to the various drawing figures, and first to FIGS. 1-3,therein is shown a barrel 10 according to one embodiment of the presentinvention. The barrel 10 includes a chamber 12 at the breach end 14. Thechamber 12 is coaxial with a rifled bore 16 which extends axially alongthe length of the barrel 10 to the muzzle 18 with external threads 19.The overall muzzle extension length L₁ does not need to be any greaterthan that necessary to accommodate the threads and to accept a muzzledevice, such as a suppressor. Unlike, prior designs, the barrel 10 ofthe present invention does not need any extra extension in length. Othernovel features of the barrel 10 cause the pistol to operate reliablywhen suppressed.

Substantially surrounding the chamber 12 is a squarish trunnion portion20 that provides lock-up edges that engage with the ejection port of aslide (not shown in FIGS. 1-3). Lacking a formally accepted name, asused herein, “trunnion portion” of the barrel is used to refer to theblockish enlarged portion surrounding the chamber in pistol designswhere this structure is used to engage with edges of the ejection portof the slide to lock the two parts together when in battery. Below thetrunnion portion 20 are barrel lugs 22 that engage the locking block ofthe pistol frame (not shown in FIGS. 1-3), causing the breach end 14 ofthe barrel to tilt downward and unlock from the slide using blow-backforces produced by a fired cartridge in a well-known manner.

The trunnion portion 20 includes a top surface 24 that is usuallyconfigured to be, for example, even with an outer surface of the slidewhen engaged in the ejection port. At the upper breach end 14 of thetrunnion portion 20, there is a hood extension 26 to support a portionof an ammunition cartridge (not shown) that may extend out of thechamber 12 when in battery. In configurations (such as the M17/M18) thatinclude a Loaded Chamber Indicator (“LCI”), the hood extension 26includes a notch 28 to accommodate the LCI. When the barrel 10 is usedin a configuration that does not include an LCI, the cartridge remainsadequately supported and the presence of the notch 28 causes nodetrimental results.

The notch 28 may be substantially laterally centered and may be, forexample, approximately 0.1300 inches in width (indicated at 30) andapproximately 0.075 inches in axial depth (indicated at 32). The overallwidth W₁ of the hood portion 26 may be adjusted, as desired, to fitassociated geometries of the slides. In preferred form, the width W₁ isselected to be at the minimum dimension within tolerance specifications,allowing it to fit in all slide styles of a model. This may be, forexample, 0.395″ to 0.400″.

According to another aspect of this embodiment, the forward edge 34 ofthe top surface 24 of the barrel lock-up block 20 may be loweredrelative to a rearward end of this surface 24. For example, the forwardedge 34 may be lowered by approximately 0.020 inches so that at least aportion 36 of the top surface 24 is inclined. In the illustratedembodiment, this inclined area 36 may extend rearward from the forwardedge 34 at least 0.275 inches (indicated at 37) an creating an angle ofabout 4.16 degrees declined from the horizontal top surface 24. Ifdesired, the inclined area 36 could extend the full length of the topsurface 24. It is the relative height of the forward edge 34 that isimportant to operation of the present invention. Accordingly, theinclined area 36 allows necessary clearance between the lock-up block 20of the barrel 10 and the slide 38 as the slide retracts.

Referring now to FIGS. 4-7, therein the barrel 10 is shown incombination with a slide 38 having a Loaded Chamber Indicator (LCI) 40.When in battery (FIGS. 4 and 5), the LCI fits into the notch 28 in thehood extension 26. The barrel 10 is “locked” with the slide 38 byengagement of the trunnion portion with the ejection port 42 opening.Release of the lock-up is determined by the engagement between the topforward edge 34 of the trunnion portion 20 of the barrel 10 and the topforward edge 44 of the ejection port 42.

FIGS. 6, 7, and 8 show the barrel 10 partially tilted to the minimumangle (represented at 50) necessary to allow the slide 38 to moverearward past the barrel trunnion 20. The barrel is supported at twoaxially spaced apart pivot points: the locking block 46 and the inneropening surfaces 48 at the forward end of the slide 38. The lockingblock 46 of the frame is schematically illustrated in FIGS. 7 and 8 asbeing substantially circular in cross-section, although this structureoften has other shapes. The exact shape of the locking block 46structure is not important to the present invention and the drawingfigures are intended to illustrate how the slide 38 can begin movingrearwardly past the barrel 10 before the barrel 10 has reached itsmaximum angle of tilt. As the slide 38 continues to move further to therear, the angle 50 of the barrel 10 relative to its in-battery axis willcontinue to increase. In part, the angle 50 will further increase as thelugs 20 fully seat on the locking block 46. Additionally, the angle willincrease as the supporting pivot points (locking block 46 and innersurfaces 48) move closer together.

Referring now to FIGS. 9 and 10, therein is shown the barrel 10installed in a slide 52 that does not include an LCI. The notch 28 inthe hood extension 26 is unfilled, which does not affect the interactionor operation of the barrel 10 and slide 52.

While one or more embodiments of the present invention have beendescribed in detail, it should be apparent that modifications andvariations thereto are possible, all of which fall within the truespirit and scope of the invention. Therefore, the foregoing is intendedonly to be illustrative of the principles of the invention. Further,since numerous modifications and changes will readily occur to thoseskilled in the art, it is not intended to limit the invention to theexact construction and operation shown and described. Accordingly, allsuitable modifications and equivalents may be included and considered tofall within the scope of the invention, defined by the following claimor claims.

What is claimed is:
 1. A replacement pistol barrel for reliableoperation when suppressed, comprising: a barrel having a chamber, athreaded muzzle end, a trunnion portion around the chamber that engagesa slide ejection port, and lugs that engage a frame locking block whenthe pistol cycles; wherein the trunnion portion has a top surface with aforward edge that engages an edge of the ejection port and a rear end,the forward edge lowered relative to the rear end and the edge of theejection port such that the slide can disengage and pass over thetrunnion portion at an earlier stage of cycling.
 2. The barrel of claim1, further comprising a hood portion extending rearward from the rearend and including a notch to receive a loaded chamber indicator when inan in-battery position.
 3. A universal handgun barrel having a trunnionportion with a top surface having a forward edge and a rear end, theforward edge is lower relative to the rear end with at least a portionof the top surface sloping upward from the forward edge to the level ofthe rear end.
 4. The barrel of claim 3, further comprising a chamberwith a breach opening and a rearwardly extending hood adjacent a top ofthe breach opening, the hood including a notch to accommodate a loadedchamber indicator, if present.